So exit out of the telnet session from rotas 3 12:56 to rock history and we can see some translations
taking place show IP net translation we can see are two not translations on the table which will time
out after a period of time wrote A or say exit of the telnet session.
Currently we've got those two net translation increase.
Let's do a why shock capture.
So I'm going to capture on the outside interface and in this case let's look at what's arriving at rodders
3.
So what's arriving on that port.
I'm going to full to this for telnet and on router 1 Telenet to rotisserie we can see the telnet data
so some telnet to negotiation taking place and we being prompted for a password.
So we see this in the Why Shock capture.
What I'll do is Antropov sort of Siska and log in and you can see see I see oh there's the Cisco loggin
password.
But what's important to notice is the traffic is coming from a source of 8 to 1 1 1 going to 8 1 1 2.
So it looks like all appears like the traffic is coming from this host going to this host.
Whereas in actual fact the traffic is coming from our one.
But in the wide shot capture we can see that all the communication is between 8 1 1 2 and 8 1 1 1.
So in this example the rotatory prompt is being sent from rotatory to Route 1.
Let's stop that capture and have a look at it on the site so I'll have a look at it on the switch.
So on this part of the network here
we'll do a full telnet once again and I'll exit out of the telnet session notice this was still part
of the same telnet session.
But notice now the address is from 10 1 1 1 2 8 1 1 2 his e x y t
and then we have the session closed.
So in this example the traffic is from this IP address as the source to this IP address as the destination.
But when it's on this interface it's changed to a 2 1 1 1.
So that's an example of that in real time.
Let's do it with two devices.
I'll do the caption now on the side but have to telnet sessions going at the same time.
So telnet wrote a one telnet to the rotisserie and router for telnet to rotisserie.
No it isn't all the output.
You only see 8 1 1 1 communicating with 8 1 1 2.
You don't see that the communication is actually from Rotto 1 and rockfall in all the output it looks
like it's the same two devices communicating with each other.
Whereas in actual fact there are multiple devices communicating here and not just a single source device
talking to a single destination device.
Now you can see that by looking at the port numbers.
So for this session the port number is 1 9 2 0 7.
That's part of the same session 1 9 2 0 7.
But notice here it's a different session number 3 2 4 5 7 3 2 4 5 7.
If we look at the net translations show IP net translation we can see the actual port numbers used by
the devices in the sessions so 3 2 4 5 7 scrolling down 6:41.
So this is the first device 10 one on one and yes the second one 10 1 1 4.
That's once again how the rod is able to differentiate between the devices.
Let's have a look at both output in the show IP translations the best output we can see when it was
created.
So this one was created two minutes and 38 seconds ago.
This one two minutes and 34 seconds ago you can see the use and the timeout and what's left on these
entries.
What's important to remember for dynamic net translations such as this is that multiple internal IP
addresses are being netted to a single external IP address.
You mustn't forget to include the overload keyword.
If you forget to that key word only one device will be able to access the internet.
Overloading enables Pat or port address translation which allows multiple internal devices to share
the same global IP address and the router that's doing the net or in this case port address translational
papped can differentiate between the sessions based on the port numbers.